Anna Nicole Smith suffered from pain most of her life, a doctor testified Wednesday, saying he treated her with prescription drugs to alleviate her chronic pain syndrome even though he considered her an addict.

"People with substance abuse disorders have the right to pain relief," said Dr. Victor Kovner, who treated Smith for three years before he sold his practice to Dr. Sandeep Kapoor, a defendant in the drug conspiracy case.

Kovner said Smith had a substance abuse disorder so severe, "she could become addicted to Jello." Treating her was a challenge, he said.

"Did you perceive her to be an addict?" Deputy District Attorney Renee Rose asked the physician.

"Yes. I believe she had addictive behaviors, but it was controlled," Kovner replied.

Kapoor, Dr. Khristine Eroshevich and Smith's boyfriend-lawyer Howard K. Stern have pleaded not guilty to charges that include conspiring to provide Smith with excessive drugs, prescribing to an addict, and prescribing to Smith under fraudulent names.

They are not charged with causing her 2007 death from a drug overdose.

Kovner said he thought Stern cared for Smith.

"He was very responsible regarding her medications," the doctor said. "He was concerned about her overusing."

Kovner said Smith told him when they met in 2001 that she was an addict and had been treated at the Betty Ford Center for addictions to Vicodin and alcohol.

Kovner later learned she had suffered from migraines and seizures as a child. She also reported pain in her back, arm and intestinal area.

After failing to find a physical cause for the pain, Kovner said he concluded Smith suffered from chronic pain syndrome and treated her with Methadone, Xanax and other drugs.

Kovner said Smith took prescription drugs for physical and emotional relief. Some of the medications he prescribed were for anxiety and depression, he added.

Kovner acknowledged under cross-examination that he and other unnamed doctors before him had prescribed medications for Smith under three different names - Anna Nicole Smith, her stage name; Vicky Lynn Marshall, her legal name; and Michelle Chase, a pseudonym.

Smith, like many celebrities, used alternate names to keep their medical information from becoming public, the doctor testified.

"It's the first time I had a patient with three names," Kovner said. "But I didn't think it was important."

Rose has suggested the multiple names would make it difficult for Smith's future doctors to track her drug use.

"This is not a good thing, to have different names," Kovner said at another point. "But there was no intention to defraud."